1. Field of the Invention
The present invention relates to an aspherical workpiece leveling method and program applicable to a contour measuring machine including a tilt correction table and the like.
2. Description of the Related Art
Generally, surface form measuring machines have been provided for measuring aspherical forms such as aspherical lenses. One of such the surface form measuring machines comprises an optical measuring probe, and a first rotating means and a second rotating means forming a certain angle therebetween. These rotating means are used to rotate the optical measuring probe to match the optical axis of the measuring probe with all directions of the normal to a target surface to be measured. This makes it possible to accurately measure the surface form of even a complicated aspherical form, as known (JP-A 11-211426, Document 1).
A surface texture measuring machine may comprise a stylus for scanning a target surface to measure the surface texture of the target surface. This machine comprises a tilt adjuster provided on a measuring table for centering a cylindrical form and a conical form, as known (JP-A 2000-266534, Document 2a; U.S. Pat. No. 6,745,616, Document 2b).
The machine disclosed in the above-described Document 1, however, requires rotations of the measuring probe about two axes having a certain angle, and accordingly causes a problem associated with the large scale of the machine. Documents 2 failed to disclose an appropriate method of leveling an aspherical workpiece with unknown design values. The machine disclosed in Documents 2 is capable of measuring the table with the workpiece mounted thereon for leveling while leaving the positional relation between the workpiece and the table unknown. In other words, it can not exclude the influence due to the workpiece attachment error always.